1. Field of the Invention
The present invention is related to a communication device and a method used in a wireless communication system, and more particularly, to a communication device and a method of handling a measurement configuration in a wireless communication system.
2. Description of the Prior Art
A long-term evolution (LTE) system supporting the 3rd Generation Partnership Project (3GPP) Rel-8 standard and/or the 3GPP Rel-9 standard are developed by the 3GPP as a successor of a universal mobile telecommunications system (UMTS), for further enhancing performance of the UMTS to satisfy increasing needs of users. The LTE system includes a new radio interface and a new radio network architecture that provides a high data rate, low latency, packet optimization, and improved system capacity and coverage. In the LTE system, a radio access network known as an evolved universal terrestrial radio access network (E-UTRAN) includes multiple evolved Node-Bs (eNBs) for communicating with multiple user equipments (UEs) and for communicating with a core network including a mobility management entity (MME) a serving gateway, etc., for Non-Access Stratum (NAS) control.
A LTE-advanced (LTE-A) system, as its name implies, is an evolution of the LTE system. The LTE-A system targets faster switching between power states, improves performance at the coverage edge of an eNB, and includes advanced techniques, such as carrier aggregation (CA), coordinated multipoint (CoMP) transmission/reception, uplink multiple-input multiple-output (UL-MIMO), etc. For a UE and an eNB to communicate with each other in the LTE-A system, the UE and the eNB must support standards developed for the LTE-A system, such as the 3GPP Rel-10 standard or later versions.
As defined in a legacy 3GPP standard (e.g., 3GPP 36.331 v12.1.0), a maximum number of measurement identities (measId) in the measurement configuration is 32. The maximum number of measurement identities (measId) is going to be changed to 64 according to recent developments in 3GPP RAN2 and 3GPP RAN4. Thus, a UE may be configured a measurement configuration including a measId greater than 32 by a source eNB. The source eNB transmits the measurement configuration to a target eNB to prepare a handover, when the source eNB initiates the handover to a target eNB for the UE. However, the target eNB may not support the measId greater than 32. In one example, the UE may transmit a measurement report including the measId greater than 32 to the target eNB, after the UE performs a radio resource control (RRC) connection re-establishment with the target eNB. The target eNB cannot process the measurement report, because the target eNB cannot recognize the measId. The target eNB cannot even release the measurement configuration, because the measurement configuration is indicated by the measId greater than 32.
Furthermore, the target eNB may not support a new sub-configuration such as widebandRSRQ-Meas-r11, t312, alternativeTimetoTrigger or a measurement priority of a carrier frequency. The target eNB is not able to release the new sub-configuration which was configured by the source eNB to the UE.
Thus, how to handle the measurement configuration is an important topic to be discussed.